Gasket and method of making



Sept. 22, 1936. HEWITT 2,055,103

GASKET AND METHOD OF MAKING Filed June 11, 1932 2 Sheets-Sheet 1 INVENTOR. ELLIS EJ-IEWITT ATTORNEY- Sept. 22, 1936. E, HEW|TT 2,055,103

GASKET AND METHQD OF MAKING Filed June 11, 1932 2 Sheets-Sheet INVENTOR. ELLIS E. HEWITT.

ATTORNEY.

Patented Sept. 22, 1936 ossm mums onssknlo v ama. meat. alleles te'l'he Westinghouse Air. Brake lull, Pl,

App cation in n.

Os-sear.

This invention relates to gaskets and to a method of making gaskets. particularly for sealing a Joint between two cooperating metal members such as the cylinder casing and cover of a 8 fluid pressure brake controlling valve device.

An object oi the invention is to provide a one piece gasket constituting a combined gasket flexible diaphragm that may be eflectively used ,to seal the joint between two casing members having metal to metal contact. and which may be conflned in a groove or recess in a face oi one of the metal members.

A iurther object the-invention is to provide a casing structure and a gasket structure therefor having the above noted characteristics, wherein the metal engaging marginal portions oi the gas- 7 kets are made oi relatively hard yielding material, such as rubber or composition, and the diaphragm portion'thereoi is made of relatively, 1 a

circular projections II and it that extend beyond .0 soft flexible material, such as rubber integrally joined to the harder marginal portion, and wherein the marginal portion oi the gasket structure is provided with sealing ribs adapted to be pressed into the body oithe structure by the casing for effecting a tight seal between the members of the casing structure.

A further object oi. the invention is to provide a gasket having integrally joined relatively hard and soft portions and a simple and inexpensive method of producing the gasket.

These and other objects of the invention that will be made apparent through the further description thereof, are attained by means of the casing and gasket structures and the method of making the gasket structure hereinafter described and illustrated in the accompanying drawings;

wherein Fig. 1 is a sectional view of a casing structure and gasket structure taken on the line l-i, of Fig. 2 and embodying features of the invention.

Fig. 2 is an elevational view of a head or cover member of the casing structure shown in Fig. l,

As'indicatedin ms. 1 and a. a. or'he'ad w i3 is provided with a recess "of irregular contour; and having a flatbottom face. which is adapted to support the inner i'a'ce oi'thegasket structure Ii. 'ihe cover ahead It is also provided with the contact'iace "and into a chamber 2i and a shallow recess 2!, respectively. in the casing II as indicated in Fig.- l. "The projection ll surrounds a chamber 28 in the cover or head I! and snugly iits wlthin the recess 22 and serves asa centering 25 member i'or properly centering the head member upon'the' casing i2 during-the assembly operation. The circularwalis 2t and ll of the projections IO and II constitute confining walls for the portions of the gasket surrounding the openings 2! and so 21inthegasketstructurell,Fig.4. H

By reierenceto Fig. 4 it will be seen that the. gasket structure ii comprisesa plurality of annular'portions II, I! and ii and a circular portion {2, integrally Joined to constitute a single one piece combined gasket and diaphragm structure, the annular portions ll, ll, and Stand the marginal portion II of the circular diaphragm portion 82 being adapted tobe clamped'between' the casing and cover members II and i8 respectively, for

sealing the ioint between said members.

The annular portions'", 2!, and "and the marginal portion ll of the diaphragm portion 32 are made of relatively hard yielding material, such as semi-hard rubber, and the said portions are provided with circular sealing ribs 34 disposed asshown inFig's'. {and 4 and which extend above the flat surface; of the gasket. structure, and when the gasket structure is in operative positionwithin the groove ,or recess ll, the ribs extend beyond the contact lace ll of the cover or head It .as shown in Fig. 3, so that when the cover is clamped in operative metal to metal contact with the casing II as indicated in Fig. l,

the ribs are pressed into the body oi the gasket a structure. Rubber or composition is substantially incompressible and consequently when the contact ribs 34 are pressed inwardly by the contact face i4 of the casing structure l2 with which they are engaged, the material in the body of the gasket structure which is confined between the outer side walls of the recess l1 and the circular walls 24 and 25 of the projections l8 and I9, fiows outwardly toward the contact face i4 of the casing l2. For this reason, the thickness of the gasket structure is made less than the depth of the recess l1, thereby providing a space 35 between the outer face of the gasket and the contact face i4 of the casing member into which the material of the gasket may fiow, when the sealing ribs 34 are pressed into the body of the gasket structure. Relatively'great pressure is required to press the sealing ribs 34 into the body of the structure and consequently an effective seal is elected.

It has been found that fluid-tight Joints without gaskets may be produced by a metal to metal contact of the casing and cover members but unless the surfaces are carefully machined and ground, slight leakage is liable to occur. A metal to metal Joint, however, in certain cases is highly desirable, as in the present instance, for insuring that the head be disposed in a predetermined position with respect to the casing in order that a predetermined volume be maintained in the chamber closed by the head. Where a gasket alone is relied upon to seal the joint between the casing and the cover, the position of the cover is dependent upon the degree of compression of the gasket. Furthermore, it has been found that where the cover is drawn tightly into contact with the body of the gasket in the endeavor to obtain a fluid-tight seal, the gasket is liable to flow and squeeze out of the space between the casing and the cover, and in the case where a diaphragm is clamped between the metal members, the diaphragm is distorted by the fiow of gasket material from between the contacting surfaces of the metal members.

Heretoiore, where metal contacts were employed to provide a fluid-tight joint, it was not practical to use a yielding packing material where it would be confined as in the present instance because of the liability of the packing material to flow into the space between the contacting surfaces while the casing parts are being drawn together, thereby preventing actual metal to metal contact of the parts and improper sealing of the cover upon the casing. By using a gasket, the thickness of which is less than the depth of the groove in which it is mounted, and having sealing ribs thereon which are adapted to be compressed into the body of the gasket structure, spaces are provided for the fiow of thegasket material as the sealing ribs are pressed into the body of the gasket structure and consequently the gasket cannot interfere with the proper positioning of the cover upon the casing in metal to metal contact. A double seal is, therefore, provided by the gasket and the metal to metal contacting surfaces. Thus a more eflicient seal is provided between the cover and the casing.

The provision of sealing ribs is particularly desirable in case of a diaphragm constituting part of the sealing gasket. It has been found that compression of the marginal portion of the usual diaphragm between two metal surfaces causes the material of the margin to fiow toward the center or toward the diaphragm and to cause it to buckle. By using sealing ribs as described above, the flow is localized in the vicinity of the sealing ribs and confined to the space between the gasket and the contact faces of the metal member. Consequently there is no tendency for the material in the margin of the diaphragm to fiow radially inwardly and cause distortion of the diaphragm.

In order to obtain an effective seal, it has been found that the margin of the gasket that is clamped between the metal members should be made ofmaterial that is relatively hard, but which will yield when the metal parts are drawn into engagement. This material does not have sufilcient flexibility for use as a diaphragm. Accordingly, the diaphragm portion of the gasket is made of a soft rubber of the required flexibility, which is joined integrally to the relatively hard marginal portion 33 during the vulcanizing operation while forming the gasket within a suitable mold.

By reference to Fig. 5, it will be seen that the diaphragm P rtion 32 of the gasket structure comprises a central portion 36 that is made of relatively soft flexible rubber in which the reinforcing fabric 31 is embedded. The outer face of the marginal portion 33 of the diaphragm portion 32 is made of substantially the same material as the annular portions 23, 29, and 3] of the gasket structure. Thus the outer contacting face of the entire gasket structure is of relatively hard material and the sealing ribs 34 are composed of the same hard material.

The gasket structure is manufactured by the following method:

A blank 4|, having the general shape and contour of the annular portions 28, 28, and 3| oi the finished gasket, is stamped from suitable raw sheet rubber of such composition that it will be relatively hard but yielding when vulcanized, the blank being provided with openings 28' and 21' corresponding to the openings 25 and 21 in the finished gasket and a third opening 40" corresponding to the opening 40 in the annular portion 3| of the finished gasket. To the under-' ing Fig. 7. A third blank 43, which is annular in is placed in a mold so that a projection 44 in the mold 45 extends through the opening 21', it being understood that the mold 45 is of the proper shape to produce the desired finished gasket structure as shown in Fig. 4.

The upper half of the mold, not shown, is then placed in registry with the mold section 45 and the mold sections are then forced together under high pressure, so as to force the raw rubber into excess rubber flowing from the mold through crevices (not shown) provided for that purpose.

The mold is then subjected to heat and the temthe shape of the finished gasket structure, the

Fig. 5, and the sealing ribs 34 on the annular portions 28, 29, and M and on the marginal portion of the diaphragm portion 32 consist of the relatively hard material. Therefore, the sealing ribs engage the contact face ll of the casing I! with uniform pressure throughout. During the vulcanizing process the three blanks of raw material are integrally joined to one another and constitute a one piece gasket structure having annular gasket fDOI'tiOl'iS and a circular diaphragm portion in which a diaphragm of relatively soft rubber is provided surrounded by a marginal portion of relatively hard rubber.

While I have disclosed but one embodiment of the invention and but one method of manufacture, it is obvious that changes may be made in the structure, and in the method of manufacture without departing from the spirit of the invention.

Having now described my invention, what I claim as new and desire to secure by Letters Patent, is:

A composite gasket and diaphragm of rubber material comprising a diaphragm portion which is relatively soft and flexible in its vulcanized state and, surrounding the peripheral edge of and integrally joined to the diaphragm portion, a gasket portion which is relatively hard and less flexible in its vulcanized state compared to the diaphragm portion, the opposite faces of the gasket portion being sealing faces and the thickness of the gasket portion between the sealing faces being greater than the thickness of the diaphragm portion so that the gasket portion assumes the clamping force and resists distortion of the diaphragm portion due to the 

